Boom suspension



' w. LEHMAN ET AL BOOM SUSPENSION Filed July 28, 1928 h/e/wer 4 6/2070 peyorflawdsofl} INVENTORS. 51 3 0, MM

A TTORNEYS.

July 7, 1931.

WISCONSIN, .ASSIGNORSQTTQ BUCYRUS-ERIE COMPANY, or sown! MILWAUKEE;

Patented'July 7, 1931" PA ENT I wminnn Lama, orsou'rn illILWAUKEE'ANfi 'raavon DAVIDSON, or MILWAUKEE,

WIsoo sI ',A CORPORATION or-pnLAwARE a J a some: SUSPENSION Ap ueati fiied ul as, Our; invention relates to new and useful improvements in boom'suspenslons. Power shovels are well known in the exeavating art; They conslst'in a maln frame,

witha" boompivoted at, its foot to the frame The prlncipal object of our invention is to provide a novel form of boom suspension,v

such that the weight ofthe boom will be properly distributed on the suspending members, and any twist imparted to the boom by the sidewise motionof the dipperwill be properly taken' up and resistedyand yet a certain degree of flexibility-oi? the boom bemain tained.

, 1 Further objects andiadvantages' our invention will be readily evident, asthe description progresses; a The invent on conslsts'ln the novel parts,

and in the combinations and arrangements.

thereof, which aredefined infthe appended claims; andof whichone embodimentis exemplified in the accompanying drawings, which are hereinafter particularly described and explained; I

erence number is applied to thesame member, or to similar members. 1 T 1 Figure i is aside elevation of so much of a power shovel as'is necessary to illustrateour invention. v r I Figure 2 -is aplan view of, the reeving'of ropes shown in Figural.

Referring'to; he drawings, it will 'be seen that 3; is the main frame of a power shovel,

boom hoist winch 6. a I a V I On a bracket 7-.on the boom.4 is mounted supporting the boomt, theA-frame '5 and the I a shipper shaft 8, carrying a saddle-block 9 through whieh the dipper-handles 10-reciprpca and w ich pivots about the shipper I v .y .7 1 hoisted position. Throughout the description, the same refsheave 28 at the point of the'boom, andthence 1928. ser al No. 290,028. 7 a H shaft 8; thus enabling the dipper-handles 10' to swing in thevertical plane which contains the boom4. The digging-dipper,-mounted on therlower end of the handles 10, andthe means for swinging anddrecipro'cating the handles, are'not shown, beingimmaterial to our present invention, and being well known 1 intheart." p The boom is raised and-lowered by means of the Winch: 6 and a boom-hoistcable 11, which passes from the Winch over a sheave 12 at the apex of the 'A-frame 5,'thence overa sheave.13 at the point of the bo0m,'thence over a sheave Mat the apex of the A-frame,

thence over a sheave-15 at l'JlIGPOlIItjOf'thG '65 boom, thence aroundtwo sheaves 16 and-17 on a yoke 18 attached to the apex of the A- frameQthene over asheave 19 at the-point of the boom, thence overa sheave 20 at the apex a of the A-frame, thenceover asheave 21 at 7 0 the point ofthe boom,'thence over asheave 22 atthe'apex of thekframe, andhenceto an anchorage 23 on theilast reaehof the rope itself. It will be readily seenithatlthe rope- 11 thus constitutes an eight-reachhoist for the boom. This exact method of hoisting the j V boom is not a feature ofour invention."

, Although it is conventional to-emplo ythe" boom-hoist cable to perform the' function of suspending theboom after it has:- been hoist: ed,idistinct means are provided by us for this purpose, and our invention inheres in thesea means.- The boom'is shown in'Figure 1 inits' i There are two boom-suspension cables, and 25..1Each passesfrom an anchorage 26- on the end of the shipper shaft 8,;thence around a sheave 27 near one extreme side of the apex of the A frame '5, thence around a back to a'nanchorage'29 adjacent the sheave 27. In the present exemplification of our in-' vention, it happens that this anchorage 29 and the sheave 27 are formed integral, as the rope 24, beinga mere support, ratherthan a running rope, does not require a sheave capaf "ble of rotation. It is to benoted that the an- 'chorages 26-are Widely spaced apartfrom each other, by virtue of theirloca'tions at the endsofthe shipper shaft 8,

as I

In order to simplify a study of the rather complicated reeving, diagrammed in Figures 1 and 2, the boom-suspension ropes 9A and have been drawn considerably broader than the boom-hoist rope 11.

It will be noticed that each of the boomsuspension ropes 2i and 25 constitutes a tworeach support for the outer end of the boom, and a one-reach support for the center of the boom.

The reasons for our particular form of boom-suspension will be readily evident from the following history of the successive in rentive steps required to solve the present problem. The main support of the boom must, of course, be at its outer end, as that is where practically all of the load of the dipper and contents is to be carried. But, with the very long booms on the enormous power-shovels now being built, such a suspension imposes a tremendous buckling strain on the center of the boom. Accordingly we provide an additional support at that point.

During the revolution of the whole shovel for dumping, the stopping and starting inertia of the dipper and its contents tends to twist the boom sidewise and also to swing the boom sidewise; to offset which tendencies, we conceived the idea of doubling the supporting means at the center of the boom, as that is where the twist is imposed.

The problem of resisting torsion in the boom, we solved by widely spacing the two anchorages of this double supporting means at the shipper shaft; and the problem of resisting the sidewise swinging, with respect to the revolving frame of the machine, of the entire boom about its base, we solved by widely spacing the two anchorages of this double supporting means at the apex of the A-frame.

So far, all that has been said would be satisfied by having the supports which run to the outer point of the boom and the supports which run to the shipper shaft be distinct from each other; but, if so built, the difficulty would be introduced that a very nice adjustment of lengths would be frequently necesi-iary, in order to prevent the stretching of one set from imposing an undue share of the supporting duty upon the other set. This difiiculty, we met by making the right-hand center-support flexible and continuous with the right-hand end-support; and similarly with the two left supports. And this had the additional advantage of lending a little flexibility to the boom.

This, however, introduced a new diliicult v, namely that the boom now tended to buckle upward. But we discovered that, by giving to that end of the rope which supported the center of the boom fewer reaches than was given to that end which supported the point of the boom, this tendency to upward buclzling would be eliminated. And this had the added advantage of placing most of the support at the point of the boom, where it belongs.

Even so, a twist given to the center of the boom, would be translated through the suspension ropes into a reverse twist at the point of the boom. This we finally succeeded in obviating by narrowly spacing the sheaves at the end of the boom. Thus the pull imparted on the ropes by a twist at the shipper shaft, is first reduced by the larger number of reaches in that part of the ropes at the point of the boom, is further reduced by the obliqueness with which these ropes lie with respect to the boom, and then is translated into an almost negligible twist of the end of the boom by the narrow spacing of the sheaves at that point. Thus we have ofi'set torsion at the center ofthe boom by very nearly a pure pull, without torsion, at the point of the boom.

By widely spacing the return of these ropes to the A-frame, we were able to provide a Still further resistance to the tendency, already mentioned, of the boom to swing about its base.

Our invention consists in the solution of these successive problems.

- To simplify the wording of the claims, the

phrases narrowly spaced and widely spaced will be used to mean laterally so spaced.

Having now particularly described and illustrated one exemplification of our invention, we wish to be understood as not there by limiting ourselves to the particular form shown, except in so far as such limitations are specified in the accompanying claims.

We claim:

1. In a power-shovel, having an 'A-"frame,

a boom, and a shipper shaft mounted at a point intermediate the ends of the boom: a boom-supension, consisting in two ropes, passing from points of attachment at the ends of the shipper shaft, thence over widely spaced sheaves at the apex of the A-rframe, thence over narrowly spaced sheaves at the outer end of the boom, and thence back to widely spaced anchorages at the apex of the A-frame.

2. In a power-shovel, having an A frame, a boom, and a dipper and dipper handle mounted on the boom for swinging in vertical plane about a fixed axis on the boom and for reciprocation with respect to said fixed axis: a boom--suspension, consisting in two ropes, passing from widely spaced "points of attachment adjacent said fixed a'Xis,'-thence over widely spaced sheaves at the apex of the A-frame, thence over narrow ly spaced sheaves at the outer end of the boom, and thence back to widely spaced. anchorages at the apex of the A-frame.

3. In a power-shovel, having an A-fr-ame, a boom, and a shipper shaft mounted at a I over widely spaced sheaves at the apex of the zoback to anchorages at the apex of the A-frame'. 5. In a power-shovel, having an A-frame',

boom-suspension,

point intermediate the ends of the boom: a consisting in two ropes, passing from points of attachment atthe ends of the shipper shaft,thence over widely spaced sheaves at the apex of the A-frame, thence over narrowly spaced sheaves at the outer end of theboom, and thence back to anchorages at the apex of the 'A-frame.

4. In a power-shovel, having an A-frame, a boom, and a dipper and dipper handle mounted on the boom for swinging in a vertical plane about a fixed axis on the boom and for reciprocation with respect to said fixed axis: a boom-suspension, consisting in two ropes, passing from widely spaced points of attachment adjacent said fixed axis, thence A-frame, thence over narrowly spaced sheaves at the outer end of the boom, and thence a boom, and a shippershaft mounted at a point intermediatethe ends of the boom: a

boom-suspension, consisting in two ropes,

passing from the ends of the shipper shaft, over widely spaced sheavesat the apex of the A-frame, to narrowly spaced points at the outer end of the boom; that part of each rope which runs fromcthe shipper shaft to the A-frame having less reaches than that part boom; that part of each rope which runs from the shipper shaft to of said rope whichruns from the A-frame tothe outer end of the boom.

6. In a power-shovel, having anA-frame,

a boom, and a dipper and dipperihandle mounted on the boom for swinging in averticalplane about a fixed axis on the'boom and for reciprocationwith respect to said.

fixed axis: a boom-suspension, consistingin two ropes, passing from widely spaced points adjacent said fixed axis, over widely spaced sheaves at the apex ofthe A-frame, to narrowly spaced points at the outer end of the thevA-frame having less reaches than that part of said rope which runs from the A-frame to the outer end I of the boom.

7. In a powe -shovel, having an A fr-ame,

a boom, and a shipper shaftmounted at a point intermediate the ends of the boom: a boom-suspension, passing from the ends of the shipper shaft, over widely spaced sheaves at the apex of the A-frame, to narrowly spaced points at the outer end of the boom; that part of each rope which runs from the shipper shaft to the A-frame having a single reach, and that part of said rope which runs from the A-frame to the outer end of the boom having a plurality of reaches.

8. In a power-shovel, having an A-frame, a boom, and a dipper and dipper handle mounted on the boom for swinging in a vertical plane about a fixed axis on the boom and for reciprocation with respect to said consisting in two ropes,

fixed axis: a boom-suspension, consisting in two ropes, passing from wldely spaced points adjacent said fixed axis, over widely spaced sheaves-at the apex of th'eA-frame, .to nar from the shipper shaft t-othe A-frame having a single reach, and thatpart of said rope which runs from the A-frame'to the outer end ofthe boom having a I plurality, of

reaches.

9'.'In a power-shovel, havinganA-frame; I

a boom, and

from the ends of the shipper shaft,

passing a shipper shaft mounted at a I point intermediate the ends of :theboom: aboomsuspension, consisting in two ropes, 4

over widely spaced sheaves at the apex of the'A-fram'e, to 'narrowlyfspaced points at and for reciprocation with respect to said fixed axis: a boom-suspens on, consisting in a I having an A-frame,

two ropes, passing from widely spaced points adjacent said fixedaxis, over widely spaced sheaves at the apex of the A-frame, to narrowly spaced points iatthe outer end of the boom.

o 11. In combination:amainiframegabooim pivoted at spaced sheaves on the frame at a point higher than the pivot foot; and two. boom-suspenof two laterally spaced anchorages approximately midway between the ends of the b oom, over one of the sheaves on the frame, thence overone of the sheaves 'on the boom, and

its' foot to the frame; two sheaves at the outerend of the boom; twolaterally,

sion ropes, each of whichrpasses from one f V thence to. an anchorage onthe frame, adjacent the sheaves on the frame.

13. In a power-shovel, having an A-frame,

a boom, and 'a dipper and dipper handle mounted on the boom for swinging in a vertical plane abouta fixed axis on the boom and for reciprocation with respect to said fixed axis: a boom-suspension, consisting in means, passing from widely spaced points on-[the boom adjacent said fixedaxis to wide'lyf of the A-frame, and 1. in means, passing from narrowly spaced I points at the outer endof the boom to" widely V 1 spaced points at the apex spaced points'at the apex of the A-frame.

1 4. In a power shovel, having an A-frame 12. In fapower-shovel, havlng an A-frame, a boom, and a shipper shaft mounted at a point intermediate the ends of the boom: ai

rowly spaced points at theouter endof the boom; that part of each: rope which-runssov and a boom, the combination of: means, cooperating with the A-frame, for hoisting the boom; and a distinct means, extending horn the A-frame to points adjacent the outer end i of the boom and points adjacent the middle of the boom, for supporting the boom, when hoisted.

15. In a power shovel, having an A-frame and aboom, the combination of: a boomhoist cable, cooperating with the A-frame; and boom-suspension cables, extending from the A-frame to points adjacent the outer end of the boom and points adjacent the middle of the boom.

In testimony whereof they affix their signatures.

WERNER LEHMAN. TREVOR DAVIDSON. 

